Bilateral activation techniques that promote symmetric, simultaneous movements of the two upper limbs have recently been applied to enhance upper limb function in chronic stroke survivors. While some researchers have reported marked improvements in movement performance with this technique, others have reported less successful outcomes. The primary objectives of the proposed project are to 1) investigate the neural mechanisms associated with bilateral activation techniques, 2) determine the class of movements most responsive to bilateral activation, 3) evaluate the additional effects of robot-assisted movements provided in a bilateral movement paradigm. To achieve these objectives, kinematic, kinetic and electromyographic measures will be used to characterize the function of the impaired limb during uni- and bi-lateral performance of specific motor tasks. Changes in impaired limb function will be analyzed both in voluntary movement conditions, where limb trajectories are generated by the individual, and in a novel robot-assisted paradigm in which the movement trajectory of the impaired limb is specified by the actual movements of the non-impaired limb. To investigate the neural pathways implicated in bilateral activation, structural and functional neural imaging techniques will be implemented to provide information on the activation and excitability of specific motor pathways during uni- and bi-lateral movement. It is envisioned that the findings of this study will characterize the specific effects of bilateral activation on impaired limb motor performance, identify the motor pathways that are engaged during bilateral activation, and potentially identify individuals and motor tasks that are most responsive to these interventions.